Observing clouds from the ground up Wenfa Ng figshare 13 Oct 2016.pdf (209.12 kB)
Observing clouds from the ground up: Skyward looking infrared and optical cameras for all weather monitoring of cloud dynamics
Dark clouds portend rain or
stormy weather and white fluffy cirrus clouds in the day point to fine weather.
Common and useful notions such as these, make apparent the utility of knowing
the color, shape and volume of clouds and their height in the atmosphere, where
a towering cumulonimbus cloud is a mini convection system in air due to the
gigantic updrafts and downdrafts within the cloud. However, current earth
observing satellites usually only gather a planar view of cloud cover. In the
case of satellites on polar orbits equipped with oblique view cameras operating
either in the infrared or visual range, partial information of cloud height is
available, but these are incomplete datasets that could not tell the story of how
dynamic interactions between earth and atmosphere is. Being a storage of water
in air, clouds hold important clues to understanding the short term evolution
of weather and the medium and long term impact of climate change. But long time
series of cloud formation, and most importantly, their dynamics is lacking from
meteorology and climate change simulation models and is a reason why
forecasting rain episodes and end of droughts remains a challenge. In lieu of
other observation data, periodic air monitoring campaigns by aircrafts do
partially fill in the large information gap on cloud dynamics, but the world is
deficient in a continuous time record of cloud dynamics of a specific locale.
Wide field infrared and optical cameras situated on the highest rooftops in a
city and which point skywards can potentially provide an answer to our quest
for better continuous understanding of cloud formation dynamics in an urban
area. Immediate impact of such information would come in forecasting rain
episodes with higher spatial and temporal resolution, while imagery of cloud
evolution and dissipation tells the story of how temperature, relative
humidity, ultraviolet radiation, aerosols and wind direction and speed combinatorically
interact with an underlying warming trend in temperature. Such information is
crucial for informing climate modeling methods, especially in calibrating
parameters associated with clouds and checking our assumptions. Beyond climate
change, more immediate use of such continuous imagery of cloud type and cover
lies in enabling a better assessment of how clouds has mitigated the impacts of
heat generation in urban heat island effects common to cities around the world.
Simple in conceptualization and without privacy concerns given the cameras’ placement
on highest rooftops in an area and their skyward glances, the dataset obtained
by continuous imaging of clouds over urban areas could provide both immediate
benefit in enhancing rain forecasts as well as serving as an important data
source for understanding clouds’ role in climate change, that up to now remain
inaccessible to most climate researchers.